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Mexican evening primrose

desert evening primrose, yellow desert evening primrose

Habit Herbs annual, moderately to sparsely strigillose and densely long-villous, sometimes also becoming glandular puberulent distally. Herbs winter-annual, caulescent to short-caulescent, long-hirsute, hairs often with reddish purple pustulate bases, especially proximally, also moderately strigillose, and glandular puberulent distally, often on leaves; from a weakly fleshy taproot.
Stems

erect to ascending, usually unbranched, or with arcuate lateral branches arising from rosette, 15–40(–60) cm.

(when present) unbranched and erect or, sometimes, few branches from near base, in robust plants stems and caudex hollow and greatly enlarged, especially toward base, densely leafy, 5–35 cm.

Leaves

in a basal rosette and cauline, basal 6–10 × 1–2.5 cm, cauline 3–7.5 × 0.8–2 cm;

blade usually grayish green, narrowly oblanceolate to narrowly oblanceolate, margins deeply lobed, lobes usually dentate;

bracts distalmost erect, revolute.

in a basal rosette, sometimes also cauline, (1.4–)6–15(–28) × (0.2–)1–3.5(–5.6) cm;

petiole (0.9–)3.5–8(–14) cm;

blade oblanceolate to linear-oblanceolate, pinnatifid or 2-pinnatifid to shallowly pinnately lobed, margins sinuate-dentate or subentire, apex obtuse.

Flowers

usually 1 opening per day near sunset;

buds erect, with free tips erect or appressed, 0.5–2.5 mm;

floral tube 23–28 mm;

sepals 5–12 mm;

petals yellow, fading orange, broadly obovate or shallowly obcordate, 6–15 mm;

filaments 4–12 mm, anthers 3–4 mm, pollen 85–100% fertile;

style 27–40 mm, stigma surrounded by anthers at anthesis.

usually 1–4, rarely more, opening per day, 1–2 hours before sunset;

sepals (7–)12–25(–30) mm;

petals yellow, fading reddish orange to purple, obcordate to obovate, (6–)13–35(–40) mm;

filaments 6–16 mm, anthers 3–10 mm;

style (32–)40–90(–100) mm, stigma exserted beyond anthers or surrounded by them.

Capsules

cylindrical, sometimes slightly enlarged toward apex, 25–45 × 2.5–3 mm.

woody in age, sigmoid or curved to nearly straight, lanceoloid to ovoid, 4-angled, 10–45(–60) × 4–8 mm, beak 4–15 mm, dehiscent 1/4–2/3 their length;

sessile.

Seeds

ellipsoid to subglobose, 0.8–1.2 × 0.3–0.5 mm.

usually numerous, in 2 rows per locule, obovoid to oblanceoloid, 3–3.5 × 1–1.4 mm, surface thickened above raphe and at distal end into U-shaped structure.

2n

= 14.

= 14.

Oenothera mexicana

Oenothera primiveris

Phenology Flowering Apr–May. Flowering Feb–May(–Jun).
Habitat Open, sandy sites. Sandy soil on flats, low hills and margins of sand dunes, along arroyos, road­sides, in desert scrub, grasslands and oak-grasslands.
Elevation 30–200 m. (100–700 ft.) 30–1600 m. (100–5200 ft.)
Distribution
from FNA
TX
[BONAP county map]
from FNA
AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Chihuahua, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Oenothera mexicana is known only from southeastern Texas (Atascosa, Aransas, Bexar, Brooks, Burleson, De Witt, Frio, Gonzales, Kenedy, Medina, Newton, Refugio, San Patricio, Waller, and Washington counties). It is self-compatible and autogamous, but not a PTH species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Oenothera primiveris has a complex variation pattern (W. L. Wagner 2005). In the western part of the range from southeastern California across southern Nevada to southern Utah counties of Emery, Kane, and Washington, and northwestern Mohave County, Arizona, plants generally have a gray appearance, with dense pubescence and larger flowers with widespread self-compatibility, but with scattered populations retaining self-incompatibility. Populations from southof the Mogollon Plateau to southern New Mexico, western Texas, Chihuahua, Sonora, and Baja California, Mexico, are greener in appearance with smaller to much smaller flowers, and are all self-compatible with occasional outcrossing or complete autogamy. The transitions between these two extremes are so extensive and more or less gradual that it is not possible to subdivide into two subspecies as has been done previously (Wagner).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Raimannia Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Eremia
Sibling taxa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. elata, O. engelmannii, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. howardii, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. primiveris, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. elata, O. engelmannii, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. howardii, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
Synonyms O. laciniata var. mexicana, O. sinuata var. hirsuta, Raimannia mexicana Lavauxia lobata, L. primiveris, O. bufonis, O. cespitosa var. primiveris, O. johnsonii, O. primiveris subsp. bufonis, O. primiveris var. bufonis, O. primiveris subsp. caulescens, O. primiveris var. caulescens, Pachylophus johnsonii
Name authority Spach: Nouv. Ann. Mus. Hist. Nat. 4: 347. (1836) A. Gray: Smithsonian Contr. Knowl. 5(6): 58. (1853)
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